Characteristics of good poka-yoke devices
Good poka-yoke devices, regardless of their implementation, share many common characteristics [5]:
they are simple and cheap. If they are too complicated or expensive, their use will not be cost-effective.
they are part of the process, implementing what Shingo calls "100%" inspection.
they are placed close to where the mistakes occur, providing quick feedback to the workers so that the
mistakes can be corrected.
Judged by these criteria, the "small dish" solution to the missing-spring problem is an excellent poka-yoke device:
It was simple.
It was cheap, involving only the cost of a small dish.
It provided immediate feedback about the quality of the work; corrections could be made on the spot